In the Fall of 2001, following the catastrophic terrorist attacks of September 11 on the United States, a series of unprecedented events unfolded that used biological agents to kill and terrorize other elements of the population. Envelopes containing highly refined spores of the species Bacillus anthracis, the causative agent of anthrax, were sent through the U.S. Postal Service to a variety of locations about the Washington/New York area. Once the envelopes were opened, the spores were released and inhaled by some of the unsuspecting bystanders in the vicinity. Although the mailings resulted in several deaths from inhalation anthrax and some cutaneous infections, the extensive use of antibiotics by all who may have been exposed saved countless lives. There were other equally dangerous side effects. The contaminated sites still had the potential of releasing spores and causing further deaths and illness. Two specific sites were the U.S. Senate Hart office building and the District of Columbia Brentwood mail center. The latter site was believed to be the source for the subsequent spread of spores throughout the postal system to many parts of the East Coast.
In order to establish the actual locations within the sites that remained contaminated, extensive traditional microbiological methods were used to swab defined areas, culture the plates onto which the swabs were applied, and then to read the plates and confirm the presence of anthrax bacilli on them. Decontamination by this process was unsuccessful and the final recourse for the two referenced sites was particularly disconcerting. The job of ridding large office buildings of anthrax contamination was an unprecedented one that required largely untried and complex techniques. The Hart Building itself was pumped full of toxic chlorine dioxide gas several times to kill any residual anthrax spores. The cleanup process took over three months at a cost of over $14 million. The Brentwood mail center was sealed off and, at the time of this application, was still closed. Mail service throughout the Northeast corridor had been seriously impacted.
The anthrax incidents referenced above showed the inadequacy of current methods, techniques, and ideas for the remediation of such dangerous particles that precipitate onto surfaces or are deposited into regions difficult to access. Identification methods have been speeded up considerably for the case of such pathogenic particles by the introduction of so-called xe2x80x9cSmart chips,xe2x80x9d yet in order to identify the collected spores, they first had to be found, suspended in a liquid carrier, and then tested for surface antigens and/or germinated. Once a particular region has been identified as the source of the targeted aerosols, its remediation presents additional challenges. If the aerosols are dangerous particles such as anthrax spores or lyophilized pathogenic bacteria, the local region is generally sterilized by a disinfectant, though for the case of bacterial spores, their resilience is often too great for all but the most toxic of such agents. After disinfection, the region must be screened for the presence of residual viable particles that may have been unaffected by the process. All of these activities require time and can be exhaustive as the efforts required to screen and clear a small region are extremely labor intensive.
A further problem unanswered concerned the source of such particles. Where did they originate? Where are the most probable locations at which residues might be found? Who is responsible for the initial dissemination of the particles and can such persons be found?
The present invention addresses the problems associated with remediating dangerous particles that may have fallen to surfaces or even be freely moving in close proximity to such regions. The invention permits the rapid characterization of the particles sought and then means to locate and remove them. It is based on the monitoring systems described in the above referenced U.S. Pat. No. 6,490,530 and provides means to find targeted particles that have precipitated onto surfaces. It also provides means to remove such particles and confirm that none remain. Finally, it provides means to track the possible perpetrators of such disseminations and/or locate evidentiary traces of the targeted and precipitated aerosols.
A device and method are disclosed whereby aerosol particles affixed to and/or lying on surfaces may be found, removed from such regions, and characterized by measuring their special light scattering properties called optical observables. These optical observables are then compared against those of a targeted particle class by which means their probable identity may be confirmed. The portable, computer-controlled particle search unit includes a light scattering chamber through which laminar flow entrained particles pass through a fine laser beam one-at-a-time. The light scattering signals generated during each particle""s passage through the beam are processed and compared to similarly processed sets of the targeted particles sought. Whenever a match is detected, the operator is informed by an alarm or visual display. Telecommunications between the particle search unit and a central station permit data processing back-up, modification of the particle search unit""s internal processing, and alarm setting.